This paper presents a new mathematical model for the pneumatic driving 6-DOF parallel robot controlled by pulse-width-modulation. The models not only overcome discontinuity of switching solenoid valve, but also change discontinuous and non-affine form into a canonical affine form. Then a sliding mode controller with fuzzy tuning is designed based on sliding mode theory and fuzzy theory and implemented on the pneumatic driving 6-DOF parallel robot position servo controlling system. The effectiveness of the controlling approach proposed here is validated by simulation data, which shows its capability of restraining the serious load coupling disturbance among channels and improving the trajectory tracking precision.